[U-Boot] TFTP timeouts, i.mx fec problem?

[Stefano Babic <sbabic@denx.de>]

Hi Ruud,

On 31/05/2013 16:36, Ruud Commandeur wrote:
> Dear Wolfgang, Stefano,
> 
> I'm pretty sure I found the cause:
> 
> For each tftp transfer the ethernet part is re-initialised. This means
> that also fec_init is called. And in fec_init this piece of code
> resides:
> 
> #ifndef CONFIG_PHYLIB
> 	if (fec->xcv_type != SEVENWIRE)
> 		miiphy_restart_aneg(dev);
> #endif
> 

Indeed, this is wanted. As design, U-Boot should not touch any interface
that is not needed and must close/reset the interface after usage. The
main reason is that the kernel is expecting a fresh powered on system,
and we get a lot of cases (USB, for instance) when the kernel cannot go
on because the bootloader let the controller in an unknown status.

> This means (in this case) that miiphy_restart_aneg() is called. And here
> the phy gets a software reset and autonegotiation restart command, wich
> can take up to 500 msces according to the datasheet. So when we would
> like to send out the 1st ARP request, the phy is busy with restart and
> negotiation. If I skip these commands, any tftp transfer is fast as
> lightning! About 150 msecs between pressing enter and the completion of
> a small file (68 bytes).
> 
> Of course, re-initialisation of all parts for each transfer sounds like
> the safest solution.

We discussed this issue many times, yes.

> But perhaps the phy could only be reset /
> initialised once after start-up. Would this be an option?

I know that there is an exception using netconsole - if the FEC driver
stops after each packet, it could not work. But again, letting the
controller in a well known status should be a must before booting the
kernel. In current code, eth_halt() is called before booting linux only
if NETCONSOLE is activated (common/cmd_bootm.c).

Best regards,
Stefano Babic

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